package harness

import (
	"context"
	"errors"
	"io"
	"log/slog"
	"net/url"
	"os"
	"strconv"
	"strings"
	"sync"
	"testing"
	"time"

	"galaxy/postgres"
	"galaxy/redisconn"
	"galaxy/rtmanager/internal/app"
	"galaxy/rtmanager/internal/config"

	"github.com/redis/go-redis/v9"
)

// Default stream key shapes used by the integration suite. They match
// the production defaults so the wire shapes asserted in `streams.go`
// are identical to what Game Lobby sees in `integration/lobbyrtm`.
const (
	StartJobsStream         = "runtime:start_jobs"
	StopJobsStream          = "runtime:stop_jobs"
	JobResultsStream        = "runtime:job_results"
	HealthEventsStream      = "runtime:health_events"
	NotificationIntentsKey  = "notification:intents"
	gameStateRootSubdir     = "game-state"
	listenAddr              = "127.0.0.1:0"
	listenerWaitTimeout     = 10 * time.Second
	readyzPollInterval      = 25 * time.Millisecond
	cleanupShutdownTimeout  = 30 * time.Second
)

// Env carries everything one integration scenario needs to drive the
// Runtime Manager process. The struct is value-typed so tests reach
// fields without intermediate getters.
type Env struct {
	// Cfg is the resolved Runtime Manager configuration handed to
	// `app.NewRuntime`. Tests inspect it for stream key shapes,
	// container defaults, and timeout knobs.
	Cfg config.Config

	// Runtime is the in-process Runtime Manager exposed for tests that
	// need to peek at internal state (`runtime.InternalServer().Addr()`).
	Runtime *app.Runtime

	// Postgres holds the per-package PostgreSQL fixture.
	Postgres *PostgresEnv

	// Redis holds the per-package Redis fixture plus a fresh client the
	// test owns.
	Redis       *RedisEnv
	RedisClient *redis.Client

	// Docker holds the per-package Docker daemon handle.
	Docker *DockerEnv

	// Lobby is the per-test stub HTTP server.
	Lobby *LobbyStub

	// Network is the unique Docker network name created for this test.
	Network string

	// EngineImageRef and PatchedImageRef are the two semver-compatible
	// engine image tags the harness builds once per package. Patch
	// scenarios point at the second tag.
	EngineImageRef  string
	PatchedImageRef string

	// GameStateRoot is the host filesystem path RTM writes per-game
	// state directories under. It lives inside `t.ArtifactDir()` so
	// failed scenarios leave the engine state behind for inspection.
	GameStateRoot string

	// InternalAddr is the bound address of RTM's internal HTTP listener
	// (resolved after Run binds the port).
	InternalAddr string
}

// EnvOptions carry per-test overrides to the harness defaults. Empty
// fields fall back to the defaults declared at the top of this file.
type EnvOptions struct {
	// ReconcileInterval overrides the periodic reconciler interval.
	// Default 500ms (so reconcile drift is observable inside a single
	// scenario timeout).
	ReconcileInterval time.Duration

	// CleanupInterval overrides the container-cleanup interval.
	CleanupInterval time.Duration

	// InspectInterval overrides the Docker inspect worker interval.
	InspectInterval time.Duration

	// ProbeInterval / ProbeTimeout / ProbeFailuresThreshold override
	// the active engine probe knobs.
	ProbeInterval          time.Duration
	ProbeTimeout           time.Duration
	ProbeFailuresThreshold int

	// GameLeaseTTL overrides the per-game Redis lease TTL.
	GameLeaseTTL time.Duration

	// StreamBlockTimeout overrides the consumer XREAD block window.
	StreamBlockTimeout time.Duration

	// LogToStderr makes the harness write the runtime's structured
	// logs to stderr; the default discards them so test output stays
	// focused on assertions.
	LogToStderr bool
}

// NewEnv stands up a fresh Runtime Manager process for the calling
// test. It blocks until the internal HTTP listener is bound; tests can
// issue REST and stream requests immediately after the call returns.
//
// `t.Cleanup` runs in reverse order: stop the runtime, close the
// runtime, close the per-test redis client, remove the docker network,
// terminate the lobby stub. Containers RTM created during the test are
// removed by the test's own cleanup paths or by the integration
// `health_test` external-action helpers.
func NewEnv(t *testing.T, opts EnvOptions) *Env {
	t.Helper()

	pg := EnsurePostgres(t)
	rd := EnsureRedis(t)
	dk := EnsureDocker(t)
	imageRef := EnsureEngineImage(t)
	TruncatePostgres(t)
	FlushRedis(t)
	network := EnsureNetwork(t)
	lobby := NewLobbyStub(t)
	stateRoot := stateRoot(t)

	cfg := buildConfig(buildConfigInput{
		PostgresDSN:        pg.DSN(),
		RedisAddr:          rd.Addr(),
		DockerHost:         resolveDockerHost(),
		Network:            network,
		LobbyURL:           lobby.URL(),
		GameStateRoot:      stateRoot,
		ReconcileInterval:  pickDuration(opts.ReconcileInterval, 500*time.Millisecond),
		CleanupInterval:    pickDuration(opts.CleanupInterval, 500*time.Millisecond),
		InspectInterval:    pickDuration(opts.InspectInterval, 500*time.Millisecond),
		ProbeInterval:      pickDuration(opts.ProbeInterval, 500*time.Millisecond),
		ProbeTimeout:       pickDuration(opts.ProbeTimeout, time.Second),
		ProbeFailures:      pickInt(opts.ProbeFailuresThreshold, 2),
		GameLeaseTTL:       pickDuration(opts.GameLeaseTTL, 5*time.Second),
		StreamBlockTimeout: pickDuration(opts.StreamBlockTimeout, 200*time.Millisecond),
	})

	logger := newLogger(opts.LogToStderr)

	ctx, cancel := context.WithCancel(context.Background())

	runtime, err := app.NewRuntime(ctx, cfg, logger)
	if err != nil {
		cancel()
		t.Fatalf("rtmanager integration: new runtime: %v", err)
	}

	runDone := make(chan error, 1)
	go func() {
		runDone <- runtime.Run(ctx)
	}()

	internalAddr := waitForListener(t, runtime)
	waitForReady(t, runtime, listenerWaitTimeout)

	var cleanupOnce sync.Once
	t.Cleanup(func() {
		cleanupOnce.Do(func() {
			cancel()
			waitCtx, waitCancel := context.WithTimeout(context.Background(), cleanupShutdownTimeout)
			defer waitCancel()
			select {
			case err := <-runDone:
				if err != nil && !isCleanShutdownErr(err) {
					t.Logf("rtmanager integration: runtime.Run returned: %v", err)
				}
			case <-waitCtx.Done():
				t.Logf("rtmanager integration: runtime did not stop within %s", cleanupShutdownTimeout)
			}
			if err := runtime.Close(); err != nil {
				t.Logf("rtmanager integration: runtime.Close: %v", err)
			}
		})
	})

	return &Env{
		Cfg:             cfg,
		Runtime:         runtime,
		Postgres:        pg,
		Redis:           rd,
		RedisClient:     rd.NewClient(t),
		Docker:          dk,
		Lobby:           lobby,
		Network:         network,
		EngineImageRef:  imageRef,
		PatchedImageRef: PatchedEngineImageRef,
		GameStateRoot:   stateRoot,
		InternalAddr:    internalAddr,
	}
}

type buildConfigInput struct {
	PostgresDSN        string
	RedisAddr          string
	DockerHost         string
	Network            string
	LobbyURL           string
	GameStateRoot      string
	ReconcileInterval  time.Duration
	CleanupInterval    time.Duration
	InspectInterval    time.Duration
	ProbeInterval      time.Duration
	ProbeTimeout       time.Duration
	ProbeFailures      int
	GameLeaseTTL       time.Duration
	StreamBlockTimeout time.Duration
}

func buildConfig(in buildConfigInput) config.Config {
	cfg := config.DefaultConfig()
	cfg.InternalHTTP.Addr = listenAddr

	cfg.Docker.Host = in.DockerHost
	cfg.Docker.Network = in.Network
	cfg.Docker.PullPolicy = config.ImagePullPolicyIfMissing

	cfg.Postgres = config.PostgresConfig{
		Conn: postgres.Config{
			PrimaryDSN:       in.PostgresDSN,
			OperationTimeout: pgOperationTimeout,
			MaxOpenConns:     5,
			MaxIdleConns:     2,
			ConnMaxLifetime:  30 * time.Minute,
		},
	}

	cfg.Redis = config.RedisConfig{
		Conn: redisconn.Config{
			MasterAddr:       in.RedisAddr,
			Password:         "integration",
			OperationTimeout: 2 * time.Second,
		},
	}

	cfg.Streams.StartJobs = StartJobsStream
	cfg.Streams.StopJobs = StopJobsStream
	cfg.Streams.JobResults = JobResultsStream
	cfg.Streams.HealthEvents = HealthEventsStream
	cfg.Streams.NotificationIntents = NotificationIntentsKey
	cfg.Streams.BlockTimeout = in.StreamBlockTimeout

	cfg.Container.GameStateRoot = in.GameStateRoot
	// Pin chown target to the current process uid/gid; the dev sandbox
	// (and unprivileged dev machines) cannot chown to root.
	cfg.Container.GameStateOwnerUID = os.Getuid()
	cfg.Container.GameStateOwnerGID = os.Getgid()

	cfg.Health.InspectInterval = in.InspectInterval
	cfg.Health.ProbeInterval = in.ProbeInterval
	cfg.Health.ProbeTimeout = in.ProbeTimeout
	cfg.Health.ProbeFailuresThreshold = in.ProbeFailures

	cfg.Cleanup.ReconcileInterval = in.ReconcileInterval
	cfg.Cleanup.CleanupInterval = in.CleanupInterval

	cfg.Coordination.GameLeaseTTL = in.GameLeaseTTL

	cfg.Lobby = config.LobbyConfig{
		BaseURL: in.LobbyURL,
		Timeout: 2 * time.Second,
	}

	cfg.Telemetry.TracesExporter = "none"
	cfg.Telemetry.MetricsExporter = "none"

	return cfg
}

func newLogger(toStderr bool) *slog.Logger {
	if toStderr {
		return slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelDebug}))
	}
	return slog.New(slog.NewTextHandler(io.Discard, &slog.HandlerOptions{Level: slog.LevelError}))
}

func stateRoot(t *testing.T) string {
	t.Helper()
	dir := t.ArtifactDir()
	root := dir + string(os.PathSeparator) + gameStateRootSubdir
	if err := os.MkdirAll(root, 0o755); err != nil {
		t.Fatalf("rtmanager integration: create game-state root %q: %v", root, err)
	}
	return root
}

func resolveDockerHost() string {
	if host := strings.TrimSpace(os.Getenv("DOCKER_HOST")); host != "" {
		return host
	}
	return "unix:///var/run/docker.sock"
}

func pickDuration(value, fallback time.Duration) time.Duration {
	if value > 0 {
		return value
	}
	return fallback
}

func pickInt(value, fallback int) int {
	if value > 0 {
		return value
	}
	return fallback
}

// waitForListener spins until `runtime.InternalServer().Addr()` returns
// a non-empty value or the deadline fires. The internal listener binds
// during `runtime.Run`, which runs in its own goroutine; this helper
// is the bridge between "Run started" and "tests can use REST".
func waitForListener(t *testing.T, runtime *app.Runtime) string {
	t.Helper()
	deadline := time.Now().Add(listenerWaitTimeout)
	for {
		if runtime != nil && runtime.InternalServer() != nil {
			if addr := runtime.InternalServer().Addr(); addr != "" {
				return addr
			}
		}
		if time.Now().After(deadline) {
			t.Fatalf("rtmanager integration: internal HTTP listener did not bind within %s", listenerWaitTimeout)
		}
		time.Sleep(readyzPollInterval)
	}
}

// waitForReady polls `/readyz` until it returns 200 or the deadline
// fires. RTM's readyz pings PG, Redis, and Docker; a successful
// response means every dependency is reachable through the runtime
// process.
func waitForReady(t *testing.T, runtime *app.Runtime, timeout time.Duration) {
	t.Helper()
	deadline := time.Now().Add(timeout)
	addr := runtime.InternalServer().Addr()
	probeURL := (&url.URL{Scheme: "http", Host: addr, Path: "/readyz"}).String()
	for {
		req, err := newRequest(context.Background(), "GET", probeURL, nil)
		if err == nil {
			resp, err := defaultHTTPClient.Do(req)
			if err == nil {
				_, _ = io.Copy(io.Discard, resp.Body)
				_ = resp.Body.Close()
				if resp.StatusCode == 200 {
					return
				}
			}
		}
		if time.Now().After(deadline) {
			t.Fatalf("rtmanager integration: /readyz did not return 200 within %s", timeout)
		}
		time.Sleep(readyzPollInterval)
	}
}

func isCleanShutdownErr(err error) bool {
	return err == nil || errors.Is(err, context.Canceled)
}

// IDFromTestName builds a deterministic-but-unique game id from the
// caller's test name. Two tests with the same name running back-to-back
// would otherwise collide on PG state through the per-test
// `TruncatePostgres` window; pinning the suffix to `Now().UnixNano()`
// rules that out.
func IDFromTestName(t *testing.T) string {
	t.Helper()
	// The container hostname is `galaxy-game-{game_id}` and must fit
	// HOST_NAME_MAX=64 chars; runc rejects longer values with
	// "sethostname: invalid argument". Cap the lowercased test-name
	// component at 36 chars and append a 16-char base36 suffix so the
	// total stays comfortably under the limit (12 + 36 + 1 + 16 = 65 →
	// trim further if needed).
	const maxNameLen = 35
	suffix := strconv.FormatInt(time.Now().UnixNano(), 36)
	prefix := strings.ToLower(strings.NewReplacer("/", "-", " ", "-").Replace(t.Name()))
	if len(prefix) > maxNameLen {
		prefix = prefix[:maxNameLen]
	}
	return prefix + "-" + suffix
}